This is a nationalization of PCT/SE00/00568, filed Mar. 23, 2000 and published in English.
1. Field of the Invention
The present invention relates to a system for marking a corner angle in a working area with the aid of light planes.
2. Description of the Related Art
In the manufacturing industry, and then in particular in the fabrication of large constructions from prefabricated components, it is sometimes difficult or troublesome to place the components together initially in correct orientation and at correct distances apart with respect to each other, prior to joining said components together by some suitable means.
In such manufacturing industries, there is normally access to a large surface area, typically a horizontal working surface (floor), on which the components can be placed in mutually appropriate positions prior to being joined together or interconnected. With the intention of ensuring that the components are positioned correctly with respect to each other, it is known from practice to project onto the working surface from a central overlying point a drawing view corresponding to a scale of 1:1 with the aid of a laser unit. However, there is a danger that the image projected in this way will be wrongly interpreted with respect to component parts that are located above the working surface, due to the fact that the projected light beams are oblique in eccentric parts of the projected image. Furthermore, component parts can, of course, screen-off the projected light beams before said beams reach the working surface. The fact that the direction of the projected light beams relative to the working surface depends on the distance from the projection centre prevents the projected light beams from being used to mark normals to the plane of the working surface. Other reproduction distortions may also occur at distances from the working surface.
One object of the invention is to provide a system with which the aforesaid drawbacks can be restricted or avoided. Another object of the invention is to provide means that enable the projection devices to be accurately aligned.
A further object of the invention is to provide a system that enables corners and angles to be readily marked with the aid of light beams in positions that can be selected by moving at least two projectors to chosen positions along a respective guide rail.
The setting arrangement of the present invention may further include a reflector such as a mirror at or beyond one end of the guide, and a light emitter which is carried by the chassis of the laser unit and which functions to direct a light beam onto the reflector, the emitter beam being parallel to the reference axis of the guide and the mirror being perpendicular to the reference axis. A light sensor detects the position at which the reflected beam impinges on the light sensor, and a control unit receives a light sensor output signal and controls a setting arrangement such as to hold the light beam reflected by the reflector parallel with the light beam emitted by the emitter.
The laser emitter of the laser unit may be supported in spaced relationship with the chassis of the laser unit through the medium of a suspension device which is adapted to allow the light plane of the laser unit to be set in a chosen orientation relative to the chassis of the laser unit.
The present invention is based on the concept of arranging a straight elongate guide along each side of a planar working surface in said working area, where each guide carries a carriage that can be moved along its guide to selected positions thereon. Each carriage carries a laser that functions to emit a light plane that intersects the working surface at a predetermined angle. The light planes of the two lasers shall also intersect each other at a predetermined angle. It is preferred in many applications to ensure that the plane of the working surface and the planes of the two laser beams intersect each other at right angles.
In other applications, the laser light planes may be perpendicular to the plane of the working surface without necessarily intersecting each other at right angles; the planes, however, conveniently retain their orientation relative to respective guides of the laser arrangement in operation. The planes of the two laser arrangements may, of course, also be set to each take a chosen angle relative to the plane of the working surface.
Each carriage will preferably coact with means for determining the position of said carriage along its guide. The system will also preferably include drive means for driving the carriage to a chosen position along its guide. The carriages may be remote controlled to predetermined positions along respective guides. In this regard, the guide arrangement may include a remote control device, for instance in the form of a hand-controlled terminal that can be carried easily by an operator. The terminal may communicate with a receiver appropriately mounted on the carriage, to send instructions to a control unit or to receive information and send this information to the terminal. The control unit or remote control device may be designed for pre-programming, so as to enable an operator to cause the two laser units to emit laser light planes that mutually intersect at predetermined positions with ease.
In a further embodiment of the invention, at least one of the guides may carry two carriages and associated laser units, for instance to establish two parallel light planes that can be moved relative to each other, either to mark desired positions or to measure distances between two points, or to measure an angle between two edges or surfaces.
In certain embodiments of the invention, the laser unit is supported from the carriage with a setting device that serves to correct laser unit directional errors originating, for instance, from an alignment error between carriage and guide, poor straightness of the guide, temperature-induced deviations, etc.
The laser emitter may also be supported away from the laser unit chassis via setting devices that enable the laser light plane to be set in chosen directions in the vertical plane or in the horizontal plane relative to the reference axis of the guide, while the chassis of the laser unit is ideally held orientated relative to the reference axis by means of said setting device.